Question

While i was developing a C++ application,

I was using a simple list<int> *somelist = new list<int>();
that contains data.

I was trying to iterate this list using something like this:

for (list<int>::iterator j=somelist->begin();j!=somelist->end();j++)
{
    //do something with *j
}

When i was doing something with the pointer j because of a chain reaction the data that i was going to access was removed from the list and no longer exists.

So, i am being prompted with an Access Violation Error Msg.

Can someone tell me how to identify if the pointer j is a bad ptr

Answer 1

With multi-threading your iterator can become invalidated if some other thread removes elements from the list. With a low-level programming such as C++, there is no way to detect this problem once it has happened. Your best bet is to “prevent this from happening.”

Use synchronization functions (e.g., WaitForSingleObject in Windows) to control access to shared STL containers.